I saw these great pics at TheCellar of La Tomatina, the tomato festival in BuÃ±ol, Spain. Apparently, 30,000 people flock to the event, which features music, parades, fireworks, a paella cook off, and one enormous tomato food fight. According to what I can see, the town seems to dump truckloads of overripe ammunition for the people to use. From Wikipedia:

Once it begins, the battle is generally every man for himself, but it is not uncommon for it to develop into girls vs. guys. Those who partake in this event are strongly encouraged to wear protective goggles and gloves. In addition, they must squish the tomatoes before throwing for safety precautions. Another rule is that no one is allowed to bring into this fight anything that may provoke someone into a more serious brawl, for instance a bottle. While the natives enjoy tearing the ragged clothing off other people, it is highly frowned upon to tear someone else's clothing. Somewhere between an hour and two hours, the fighting ends and the cannon is fired once more to signal the end. At this point no more tomatoes can be thrown. The cleaning process involves the use of fire trucks to spray down the streets, with water provided from a Roman aqueduct. People find water to wash themselves, most likely at the BuÃ±ol River.